1. Field of the Invention
This invention relates to materials handling systems and, more particularly, to selection and conveyance of material within a materials handling system.
2. Description of the Related Art
An enterprise that receives, consumes, transforms or distributes material during the course of its operations may implement a materials handling system to coordinate how material is managed within the enterprise. For example, in a manufacturing context, material may include raw materials, feedstocks, parts, etc. that may arrive at a manufacturing facility for processing as well as intermediate or finished goods resulting from the manufacturing process. Similarly, in a distribution context, retailers, wholesalers and other types of distributors may receive materials such as goods or products and distribute them to clients or customers.
Material may be stored as inventory within an inventory facility and made available for ordering or use by clients or customers. For example, in a manufacturing context, a client may include a step of a manufacturing process that includes a particular type of material as an input, while in a retail context, a client may include a customer who places an order for a product. Often, like items are stored together within inventory to facilitate inventory tracking and management. For example, items having a common Universal Product Code (UPC), Stock-Keeping Unit (SKU) code, or other designation (including proprietary designations) may be stored together within inventory.
When retrieval of material from inventory is necessary, for example in response to a client's order or to replenish a manufacturing process, one or several inventory items must be retrieved or “picked” from inventory and prepared for delivery to the requestor or recipient. In an inventory environment that includes a large number of many different items, multiple different items may be concurrently requested or ordered by the same requestor. For example, a customer may place an order for a number of dissimilar items, or a process may require a number of different materials before it can proceed. In such cases, it may be highly inefficient for a single employee or agent to pick every item for a given order. For example, the different items specified by a given order may be stored at mutually remote locations within the inventory facility, which would require a single picker to traverse a long path through the facility.
To improve productivity, a materials handling system may use multiple item pickers distributed throughout an inventory facility, such that more than one picker may select items for a given order. Such a division of labor may reduce the overall time required to complete picking for a given order in comparison to a single picker traversing the entire facility. However, while reducing the overall time to pick a particular order through division of labor may increase the efficiency of completing that particular order, it may in some instances only marginally increase the overall efficiency of the pickers involved. For example, an item picker instructed to pick portions of multiple different orders may still traverse a long path through the inventory facility relative to the number of items picked.
Further, dividing orders for material from a single requestor among multiple pickers requires that the items be subsequently sorted to associate the proper items with each requestor. For example, a given customer may place an order specifying multiple items. Each of several pickers may select an aggregation of items, where different ones of the items specified in the given order may be selected by different pickers. Consequently, a subsequent sort operation to select the proper items for the given order from the aggregations of items returned by each respective picker is required. Such sorting may be labor intensive if performed manually. Mechanical sorting solutions exist that are suitable for sorting certain types of inventory items according to individual orders (e.g., the Crisplant® sorter). However, such solutions are typically expensive in both cost and floor area. Implementations using such solutions typically do not scale well as inventory throughput demands increase, since implementing a fractional solution is often impractical if not impossible. For example, to address a 30-40% increase in order throughput requirement may require purchasing an entire new sorting system, effectively doubling throughput capacity despite leaving 60-70% of the new capacity unutilized. Finally, even if manual sorting is employed, pickers may still need to convey their picked items to the sorting area(s). Such conveying may require pickers to spend a substantial amount of time in transit within an inventory facility, which may decrease time available for picking items for other orders.